Female Reproductive System
The Highlights
Hormones of the Female
Reproductive Cycle
• Control the reproductive cycle
• Coordinate the ovarian and uterine cycles
Hormones of the Female
Reproductive Cycle
• Key hormones include:
– FSH
• Stimulates follicular development
– LH
• Maintains structure and secretory function of corpus
luteum
– Estrogens
• Have multiple functions
– Progesterones
• Stimulate endometrial growth and secretion
Female Reproductive Organs
• Ovary: female gonad
• Uterine Tubes (fallopian tube, oviduct)
- three parts: infundibulum, ampulla, isthmus
The Female Reproductive System in Midsagital View
Figure 28.13
The Ovaries and Their Relationships to the
Uterine Tube and Uterus
Figure 28.14a, b
The Uterus
• Muscular organ
– Mechanical protection
– Nutritional support
– Waste removal for the developing embryo and fetus
• Supported by the broad ligament and 3 pairs of
suspensory ligaments
Uterine Wall Consists of 3
Layers:
• Myometrium – outer muscular layer
• Endometrium – a thin, inner, glandular mucosa
• Perimetrium – an incomplete serosa continuous
with the peritoneum
• The site of implantation of developing embryo
• And 3 parts: fundus, body, and cervix
Female Accessory Sex Organs: Uterus
• Uterine endometrium has two layers:
- basal layer
- functional layer: built up and shed each cycle
The Uterus
Figure 28.18c
The Uterine Wall
Figure 28.19b
The Uterine Cycle
To be discussed below
Figure 28.20
Functions of the Ovary
• Production of a mature oocyte, capable of
fertilization and embryonic development.
• Production of ovarian steroids (estradiol,
progesterone).
• Production of gonadal peptides (inhibin, activin).
Structural Organization of the Ovary
• The main functional unit of the ovary is the
follicle.
• Follicles are composed of the oocyte,
granulosa cells, and theca cells.
Stages of Follicular Growth
• Follicles are present in a number of
different stages of growth:
- primordial follicles (resting)
- primary, secondary, and antral follicles
- preovulatory (Graafian) follicles
The Corpus Luteum
• After the preovulatory follicle ovulates
(releases its egg), it forms the corpus
luteum.
FEMALE REPRODUCTIVE SYSTEM
 OVARY
The Ovarian Cycle
3 to 5 million OOGONIA differentiate into
PRIMARY OOCYTES during early development
OOCYTES becomes surrounded by squamous
(follicular) cells to become PRIMORDIAL FOLLICLES
most PRIMORDIAL FOLLICLES undergo
atresia leaving 400,000 at birth
oocytes at birth arrested at
Meiosis I (prophase)
FEMALE REPRODUCTIVE SYSTEM
 OVARY
THREE STAGES OF OVARIAN FOLLICLES CAN
BE IDENTIFIED FOLLOWING PUBERTY:
(each follicle contains one oocyte)
(1) PRIMORDIAL FOLLICLES
OOGENESIS
- very prevalent; located in the
periphery of the cortex
- a single layer of squamous follicular
cells surround the oocyte
(2) GROWING FOLLICLES
- three recognizable stages:
(a) early primary follicle
(b) late primary follicle
(c) secondary (antral) follicle
(3) MATURE (GRAAFIAN) FOLLICLES
- follicle reaches maximum size
FEMALE REPRODUCTIVE SYSTEM
 OVARIAN FOLLICLES
(1) PRIMORDIAL FOLLICLES
(2) GROWING FOLLICLES
(a) early primary follicle
- follicular cells still unilaminar but now are cuboidal in appearance
- oocyte begins to enlarge
(b) late primary follicle
- multilaminar follicular layer; cells now termed granulosa cells
- zona pellucida appears; gel-like substance rich in GAGs
- surrounding stromal cells differentiate into
theca interna and theca externa
(b) secondary (antral) follicle
- cavities appear between granulosa cells forming an antrum
- follicle continues to grow
- formation of cumulus oophorus and corona radiata
(3) MATURE (GRAAFIAN) FOLLICLES
FEMALE REPRODUCTIVE SYSTEM
 HORMONAL REGULATION OF
OOGENSIS AND OVULATION
HYPOTHALAMUS release of GnRF which
stimulates release of LH and FSH from the
adenohypophysis (ANTERIOR PITUITARY)
Neuroendocrine Regulation of Ovarian
Functions
CNS
hypothalamus
GnRH
Pituitary
FSH
LH
E2, P
inhibin,
activin
OVARY
Follicle
Development
Ovulation
Luteinization
Effects of GnRH on Gonadotropins
• GnRH is released in a pulsatile manner,
stimulating the synthesis and release of LH and
FSH.
• GnRH acts through its receptor on the pituitary
gonadotroph cells, stimulating production of
phospholipase C.
• Recall that IP3 pathway causes gonadotropin
release, while the DAG/PKC pathway causes
gonadotropin synthesis.
Actions of FSH on Granulosa Cells

FSH

AC
ATP
cAMP
Gs
Gene Expression
Steroidogenic
enzymes
PKA
LH Receptor
CREB
CRE
Inhibin Subunits
Plasminogen
Ovarian Estradiol Production
LH
Theca cells
androgens
aromatase
Granulosa cells
FSH
estradiol
Regulation of Progesterone Production
• Progesterone is produced from theca cells, mature
granulosa cells, and from the corpus luteum.
• In this case, gonadotropins induce expression of
- steroidogenic acute regulatory protein
- P450 side chain cleavage
Actions of Estradiol
• Estradiol also has important actions in a number of
other tissues:
- causes proliferation of uterine endometrium
- increases contractility of uterine myometrium
- stimulates development of mammary glands
- stimulates follicle growth (granulosa cell
proliferation)
- effects on bone metabolism, hepatic lipoprotein
production, genitourinary tract, mood, and cognition
• Effects are mediated through the intracellular
estrogen receptors (alpha and beta), and possible
membrane effects.
Actions of Progesterone
• Progesterone exerts positive and negative
feedback effects on gonadotropin synthesis and
release.
• Progesterone also acts on many tissues:
- stimulates secretory activity of the uterine
endometrium
- inhibits contractility of the uterine myometrium
- stimulates mammary growth
• The actions of progesterone are mediated through
an intracellular P receptor, which acts as a
transcription factor.
FEMALE REPRODUCTIVE SYSTEM
The Menstrual Cycle
 HORMONAL REGULATION OF OOGENSIS AND OVULATION
FOLLICULAR PHASE
OVULATION
LUTEAL PHASE
10-20 primordial follicles begin to develop
in response to FSH and LH levels
theca and granulosa cells transform into the corpus
luteum and secrete large amounts of progesterone
FSH and LH stimulate theca and granulosa
production of estrogen and progesterone
if fertilization does not occur, corpus luteum
degenerates ... if fertilization does occur, HCG
released from the embryo maintains corpus luteum
surge of LH induces ovulation
FEMALE REPRODUCTIVE SYSTEM
The Menstrual Cycle
 HORMONAL REGULATION OF OOGENSIS AND OVULATION
OVULATION:
sharp surge in LH
with simulataneous
increase in FSH
Meiosis I resumes;
oocyte and surrounding
cumulus break away and
are extruded
oocyte passes into
oviduct
ECTOPIC
IMPLANTATIONS
The Menstrual Cycle
• Women have ovulatory cycles of about 28 days in
length.
• Day 1 of the cycle is defined as the first day of
menstruation.
• There are two phases of the cycle, named after
ovarian and uterine function during that phase:
- first two weeks: follicular or proliferative stage
- second two weeks: luteal or secretory stage
• The preovulatory gonadotropin surges occur in the
middle of the cycle (around day 14).
The Menstrual Cycle: The Ovary
• Follicular phase: small antral follicles develop, a
dominant follicle is selected and grows to the
preovulatory stage.
• Midcycle: the gonadotropin surges cause
ovulation of the dominant follicle.
• Luteal phase: the corpus luteum forms and
becomes functional, secreting large amounts of
progesterone, followed by estradiol (results in
negative feedback, not positive feedback, because
P increases before E2).
• If pregnancy does not take place, the corpus
luteum regresses, and P and E2 levels decrease.
The Menstrual Cycle: The Uterus
• Proliferative stage: increasing estradiol levels
stimulate proliferation of the functional layer of
the uterine endometrium.
- Results in increased thickness of the
endometrium.
- Increased growth of uterine glands (secrete
mucus) and uterine arteries.
• Secretory stage: progesterone acts on the
endometrium.
- uterine glands become coiled and secrete more
mucus
- uterine arteries become coiled (spiral arteries)
The Menstrual Cycle: The Uterus
• If pregnancy doesn’t occur, P and E2 levels
decrease at the end of the secretory stage.
- vasospasm of arteries causes necrosis of tissue
- loss of functional layer with bleeding of uterine
arteries (menstruation)
FEMALE REPRODUCTIVE SYSTEM
 UTERUS
ENDOMETRIUM
undergoes cyclic changes which prepare
it for implantation of a fertilized ovum
TWO LAYERS:
(1) FUNCTIONAL LAYER (stratum functionalis)
- BORDERS UTERINE LUMEN
- SLOUGHED OFF AT MENSTRATION
- CONTAINS UTERINE GLANDS
(2) BASAL LAYER (stratum basale)
- RETAINED AT MENSTRATION
- SOURCE OF CELLS FOR REGENERATION OF
FUNCTIONAL LAYER
STRAIGHT AND SPIRAL ARTERIES
FEMALE REPRODUCTIVE SYSTEM
 HORMONAL REGULATION OF UTERINE CYCLE
(1) PROLIFERATIVE PHASE
concurrent with follicular maturation and influenced by estrogens
(2) SECRETORY PHASE
concurrent with luteal phase and influenced by progesterone
(3) MENSTRUAL PHASE
commences as hormone production by corpus luteum declines
Male Reproductive System
The Highlights
The Male Reproductive System in Midsagital View
Figure 28.1
MALE REPRODUCTIVE SYSTEM
 TESTIS
TUNICA ALBUGINEA
- thick connective tissue capsule
- connective tissue septa divide
testis into 250 lobules
- each lobule contains 1-4
seminiferous tubules and
interstitial connective tissue
(1) SEMINIFEROUS TUBULES
- produce sperm
INTERSTITIAL TISSUE
- contains Leydig cells which
produce testosterone
(2) RECTUS TUBULES
(3) RETE TESTIS
(4) EFFERENT DUCTULES
(5) EPIDIDYMIS
MALE REPRODUCTIVE SYSTEM
 SPERMATOGENESIS
SPERMATOGONIA
1º SPERMATOCYTE
2º SPERMATOCYTE
SPERMATIDS
SPERMATIDS
2º SPERMATOCYTE
1º SPERMATOCYTE
SERTOLI CELLS:
- columnar with adjoining lateral processes
- extend from basal lamina to lumen
- Sertoli-Sertoli junctions divide
seminiferous tubules into basal and
adluminal compartments
SERTOLI
CELLS
SPERMATOGONIA
Basal Lamina
Spermatogonia (stem cells)
2n
2n
2n
mitosis
Daughter cell Type A
spermatogonium
remain at basal lamina
as a precursor cell
Daughter cell Type B Spermatagonium
Moves to adluminal compartment
n
1° spermatocyte
Meiosis I completed
n
n
Meiosis II
2° spermatocyte
n
n
n
n
n
n
n
n
Early spermatids
Late spermatids
MALE REPRODUCTIVE SYSTEM
 SPERMATOGENESIS
THREE PHASES:
(1) Spermatogonial Phase (Mitosis)
(2) Spermatocyte Phase (Meiosis)
(3) Spermatid Phase (Spermiogenesis)
- acrosome formation; golgi granules fuse to
form acrosome that contains hydrolytic
enzymes which will enable the
spermatozoa to move through the
investing layers of the oocyte
- flagellum formation; centrioles and
associate axoneme (arrangement of
microtubules in cilia)
- changes in size and shape of nucleus;
chromatin condenses and shedding of
residual body (cytoplasm)
MALE REPRODUCTIVE SYSTEM
 HORMONAL REGULATION OF
MALE REPRODUCTIVE FUNCTION
HYPOTHALAMUS REGULATES ACTIVITY OF
ANTERIOR PITUITARY (ADENOHYPOPHYSIS)
ADENOHYPOPHYSIS SYNTHESIZES HORMONES
(LH and FSH) THAT MODULATE ACTIVITY OF
SERTOLI AND LEYDIG CELLS
Luteinizing Hormone (LH): stimulates testosterone
production by Leydig cells
Follicle Stimulating Hormone (FSH): stimulates production of sperm
in conjunction with testosterone by regulating activity of Sertoli cells
SERTOLI CELLS STIMULATED BY FSH AND TESTOSTERONE RELEASE
ANDROGEN BINDING PROTEIN WHICH BINDS TESTOSTERONE;
THEREBY INCREASING TESTOSTERONE CONCENTRATION WITHIN THE
SEMINIFEROUS TUBULES AND STIMULATING SPERMATOGENESIS